Russia's upper house of parliament has approved the international Kyoto Protocol on climate change.
The treaty need only be signed by Putin before it can come into force
The United Nations treaty now needs only President Vladimir Putin's signature for formal ratification.
Russia's Federation Council voted by 139-1 with one abstention to approve the protocol, which urges signatories to cut their greenhouse gas emissions.
The climate pact should come into force early next year despite a refusal of the US to ratify it.
The State Duma, Russia's lower house of parliament, voted 334-73 last week to approve the treaty.
Following his signature, which is regarded as a formality, Mr Putin will pass on his country's ratification of the pact to the UN.
Speaking before Wednesday's vote, Mikhail Margelov, head of the Federation Council's foreign affairs committee, said efforts to tackle climate change would be "doomed to failure" without senators' support.
Environmental campaigners have welcomed Russia's move.
Russia's agreement was essential because the protocol could only come into force when ratified by developed nations that account for at least 55% of global greenhouse emissions.
After the US pulled out in 2001, that figure could only be reached with the support of Russia, which accounts for 17% of world emissions.
Early next year, Kyoto signatories must start making cuts that will reduce emissions of six key greenhouse gases to an average of 5.2% below 1990 levels by 2012.